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Kepler Mission
AndyG
post Aug 26 2010, 05:24 PM
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Hmmm..."Kepler 9". (Sounds a bit Star Trek to me!)

Two transiting saturnoids, orbiting a "sun-like star" in a 2:1 resonance of 38 days and 19 days. Orbital parameters change slightly over time, suggesting a third planet candidate. This is a possible hot-Earth of 1.5 Earth-diameters much closer in.

The news in brief: "Demonstration of transit-timing alteration allowing for otherwise unseen planets to have their orbits calculated - allowing for 'discovery' of planets that may lie in the habitable zone of stars even if they're not seen transiting."
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Norm Hartnett
post Aug 26 2010, 06:24 PM
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umph. huh.gif

First detection of multiple planets in one system using transits. (Is that right?) blink.gif

Anyway, http://kepler.nasa.gov/Mission/discoveries/

Count of confirmed planets is now 7.
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punkboi
post Aug 26 2010, 07:00 PM
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The Kepler Planet Counter on the website should be updated soon...it still stands at 005.


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Mirek
post Aug 28 2010, 06:43 PM
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There is the link to very interesting paper about recent discovery.
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Vultur
post Sep 10 2010, 02:59 AM
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QUOTE (punkboi @ Aug 26 2010, 07:00 PM) *
The Kepler Planet Counter on the website should be updated soon...it still stands at 005.


It's been updated; 007 now.
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Guest_cassioli_*
post Sep 21 2010, 08:46 AM
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Don't know if it has already been posted, anyway data about all Kepler planets candidates are available online:
http://archive.stsci.edu/kepler/planet_candidates.html

Most of the planets have periods below 40 days... and it's quite obvious, as data have been collected for 43 days; but I don't understand how planets with >100 days period can be in the list. huh.gif

I can't understrand all of the data: is it possibile to obtain from them planets min/max distance from its star and planet surface temperature?

For example, this planet has 1.5 Earth radius:
http://archive.stsci.edu/kepler/data_searc...pler_id=3541800

But how far from its star is it, and which is (or could be) planet temperature (not considering possible greenhouse effects)?
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Hungry4info
post Sep 21 2010, 09:31 AM
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You can make a rough assumption of the stellar mass from the given stellar radius. Then with the orbital period of the planet in hand, calculate its semi-major axis.


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Guest_cassioli_*
post Sep 21 2010, 10:00 AM
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QUOTE (Hungry4info @ Sep 21 2010, 10:31 AM) *
You can make a rough assumption of the stellar mass from the given stellar radius. Then with the orbital period of the planet in hand, calculate its semi-major axis.

I don't know which formulas to use.
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remcook
post Sep 21 2010, 11:34 AM
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I thought they got stellar mass from things like stellar type. How would you know the radius of the star from direct measurements?

Temperatures you can estimate by balancing the energy from incoming starlight with outgoing thermal radiation (http://en.wikipedia.org/wiki/Effective_temperature)
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Hungry4info
post Sep 21 2010, 08:00 PM
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QUOTE (remcook @ Sep 21 2010, 06:34 AM) *
I thought they got stellar mass from things like stellar type. How would you know the radius of the star from direct measurements?

If you know the brightness and temperature (from colour), you can estimate the radius.


QUOTE ("cassiolo")
I don't know which formulas to use.

Kepler's Third Law of planetary motion.


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Guest_cassioli_*
post Sep 22 2010, 07:02 AM
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QUOTE (Hungry4info @ Sep 21 2010, 09:00 PM) *
Kepler's Third Law of planetary motion.

I read "K" is 1 for Earth+Sun, but can't understand how to calculate it for other systems.
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remcook
post Sep 22 2010, 07:35 AM
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QUOTE (Hungry4info @ Sep 21 2010, 08:00 PM) *
If you know the brightness and temperature (from colour), you can estimate the radius.


Indeed, so this is not possible with Kepler alone, right?
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Hungry4info
post Sep 22 2010, 02:01 PM
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QUOTE (remcook @ Sep 22 2010, 02:35 AM) *
Indeed, so this is not possible with Kepler alone, right?


Actually, since Kepler is a photometer, it's quite capable of determining a star's brightness and colour, the first of which are how it's looking for planets.

QUOTE ("cassioli")
I read "K" is 1 for Earth+Sun, but can't understand how to calculate it for other systems.

From Wikipedia's page, where P is the orbital period, and a is the semi-major axis.





Since you know three of the four values, you can easily calculate the fourth, missing value.


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Vultur
post Sep 22 2010, 02:05 PM
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I don't understand where the temperatures are coming from. 6867155 has a period of 206 days, and the star is 0.927 solar radii. So if the star is mostly Sunlike, and the potential planet has a Venus-like period; why does it have a predicted temperature of 4118 Kelvin? Or are those the star surface temperatures?
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Mongo
post Sep 22 2010, 02:34 PM
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QUOTE (Vultur @ Sep 22 2010, 02:05 PM) *
I don't understand where the temperatures are coming from. 6867155 has a period of 206 days, and the star is 0.927 solar radii. So if the star is mostly Sunlike, and the potential planet has a Venus-like period; why does it have a predicted temperature of 4118 Kelvin? Or are those the star surface temperatures?


That is the star's photospheric temperature.
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